@misc{PoulikakosGutscheMcPeaketal.2015, author = {Poulikakos, Lisa and Gutsche, Philipp and McPeak, Kevin and Burger, Sven and Niegemann, Jens and Hafner, Christian and Norris, David}, title = {A Far-Field Interpretation of the Optical Chirality}, journal = {Frontiers in Nanophotonics (Congressi Stefano Franscini)}, year = {2015}, abstract = {A chiral structure is not super-imposable with its mirror image. Most commonly found in organic molecules, chirality can also occur in other systems, such as electromagnetic fields, where circularly polarized light is the most widespread example. Chiral electromagnetic fields can be a useful tool for biosensing applications. In particular, it has been shown that chiral plasmonic nanostructures have the ability to produce strongly enhanced chiral near-fields. Recently, our group has developed chiral plasmonic nanopyramids, which have the ability to focus chiral near-fields at their tip. This could enable chiral sensing at the single-molecule level. Chiral near-fields can be characterized in terms of the "optical chirality density". This time-even and parity-odd pseudoscalar was first derived by Lipkin and was found to follow a conservation law analogous to the energy conservation of electromagnetic fields. More recently, Tang and Cohen identified the physical meaning of the "optical chirality density" as the degree of asymmetry in the excitation rate of a chiral molecule. However, how this near-field interpretation of the optical chirality could translate into the far-field is not well understood. Here, we formulate a far-field interpretation by investigating the conservation law for optical chirality in matter, and performing time-averaging in analogy to Poynting's Theorem. In parallel to extinction energy, we define the "global chirality" as the sum of chirality dissipation within a material and the chirality flux leaving the system. With finite-element simulations, we place a dipole source at locations of enhanced local chirality and investigate the global chirality and ellipticity of emitted light in the far-field. Interestingly, we find that lossy materials with a complex dielectric function have the ability to generate global chirality when excited by achiral light. In particular, chiral plasmonic nanostructures are found to act as effective global chirality generators. The global interpretation of optical chirality provides a useful tool for biosensing applications with chiral plasmonic nanostructures, where the detection is routinely performed in the far-field.}, language = {en} } @inproceedings{BurgerGutscheHammerschmidtetal.2015, author = {Burger, Sven and Gutsche, Philipp and Hammerschmidt, Martin and Herrmann, Sven and Pomplun, Jan and Schmidt, Frank and Wohlfeil, Benjamin and Zschiedrich, Lin}, title = {Hp-finite-elements for simulating electromagnetic fields in optical devices with rough textures}, volume = {9630}, booktitle = {Proc. SPIE}, arxiv = {http://arxiv.org/abs/1510.02607}, doi = {10.1117/12.2190119}, pages = {96300S}, year = {2015}, language = {en} } @article{WolffGutscheSteeletal.2015, author = {Wolff, Christian and Gutsche, Philipp and Steel, Michael J. and Eggleton, Benjamin J. and Poulton, Christopher G.}, title = {Impact of nonlinear loss on stimulated Brillouin scattering}, volume = {32}, journal = {J. Opt. Soc. Am. B}, number = {9}, arxiv = {http://arxiv.org/abs/1505.02517}, doi = {10.1364/JOSAB.32.001968}, pages = {1968 -- 1978}, year = {2015}, abstract = {We study the impact of two-photon absorption (2PA) and fifth-order nonlinear loss such as 2PA-induced free-carrier absorption in semiconductors on the performance of stimulated Brillouin scattering devices. We formulate the equations of motion including effective loss coefficients, whose explicit expressions are provided for numerical evaluation in any waveguide geometry. We find that 2PA results in a monotonic, algebraic relationship between amplification, waveguide length, and pump power, whereas fifth-order losses lead to a nonmonotonic relationship. We define a figure of merit for materials and waveguide designs in the presence of fifth-order losses. From this, we determine the optimal waveguide length for the case of 2PA alone and upper bounds for the total Stokes amplification for the case of 2PA as well as fifth-order losses. The analysis is performed analytically using a small-signal approximation and is compared to numerical solutions of the full nonlinear modal equations.}, language = {en} } @inproceedings{GregersenRosenkrantzdeLassonHagedornFrandsenetal.2017, author = {Gregersen, Niels and Rosenkrantz de Lasson, Jakob and Hagedorn Frandsen, Lars and H{\"a}yrynen, Teppo and Lavrinenko, Andrei and Moerk, Jesper and Wang, Fengwen and Sigmund, Ole and Kim, Oleksiy S. and Breinbjerg, Olav and Ivinskaya, Aliaksandra and Gutsche, Philipp and Burger, Sven}, title = {Benchmarking five computational methods for analyzing large photonic crystal membrane cavities}, booktitle = {Numerical Simulation of Optoelectronic Devices (NUSOD)}, doi = {10.1109/NUSOD.2017.8010005}, pages = {89}, year = {2017}, language = {en} } @inproceedings{NovitskyRosenkrantzdeLassonHagedornFrandsenetal.2017, author = {Novitsky, Andrey and Rosenkrantz de Lasson, Jakob and Hagedorn Frandsen, Lars and Gutsche, Philipp and Burger, Sven and Kim, Oleksiy S. and Breinbjerg, Olav and Ivinskaya, Aliaksandra and Wang, Fengwen and Sigmund, Ole and H{\"a}yrynen, Teppo and Lavrinenko, Andrei and M{\o}rk, Jesper and Gregersen, Niels}, title = {Comparison of five computational methods for computing Q factors in photonic crystal membrane cavities}, booktitle = {19th International Conference on Transparent Optical Networks (ICTON)}, doi = {10.1109/ICTON.2017.8024813}, year = {2017}, language = {en} } @article{PoulikakosGutscheMcPeaketal.2016, author = {Poulikakos, Lisa and Gutsche, Philipp and McPeak, Kevin and Burger, Sven and Niegemann, Jens and Hafner, Christian and Norris, David}, title = {The Optical Chirality Flux as a Useful Far-Field Probe of Chiral Near Fields}, volume = {3}, journal = {ACS Photonics}, arxiv = {http://arxiv.org/abs/1601.06716}, doi = {10.1021/acsphotonics.6b00201}, pages = {1619}, year = {2016}, language = {en} } @misc{GutschePoulikakosBurgeretal.2016, author = {Gutsche, Philipp and Poulikakos, Lisa and Burger, Sven and Hammerschmidt, Martin and Schmidt, Frank}, title = {Optical chirality: conservation law in arbitrary space}, journal = {606. WE-Heraeus-Seminar on Nanophotonics and Complex Spatial Modes of Light}, year = {2016}, abstract = {The introduction of the near-field quantity of optical chirality has emerged in various numerical and few experimental studies of local chirality enhancement due to its relation to the excitation rate of chiral molecules. This time-even pseudoscalar has been dismissed as being a higher-order version of helicity. Nevertheless, we revisit the derivation of the underlying conservation law and define optical chirality in media similar to. We identify the mechanism of chirality conversion by either inhomogeneous or anisotropic space to complement the conservation of optical chirality. The conservation law of optical chirality in arbitrary space enables the extension of the concept of polarization to the near-field where no distiniguished propagation direction of light is present. We show that the connection of electromagnetic energy and optical chirality provide the ability to define a circular polarization basis in time-harmonic near-field analysis. In order to illustrate our theory, we present electromagnetic field simulations of simple as well as more complex nanostructures. Results using the well-known far-field polarization concept are readily reproduced and extended from the point of view of chirality conversion.}, language = {en} } @article{WolffGutscheSteeletal.2015, author = {Wolff, Christian and Gutsche, Philipp and Steel, Michael J. and Eggleton, Benjamin J. and Poulton, Christopher G.}, title = {Power limits and a figure of merit for stimulated Brillouin scattering in the presence of third and fifth order loss}, volume = {23}, journal = {Opt. Express}, number = {20}, arxiv = {http://arxiv.org/abs/1508.02458}, doi = {10.1364/OE.23.026628}, pages = {26628 -- 26638}, year = {2015}, abstract = {We derive a set of design guidelines and a figure of merit to aid the engineering process of on-chip waveguides for strong Stimulated Brillouin Scattering (SBS). To this end, we examine the impact of several types of loss on the total amplification of the Stokes wave that can be achieved via SBS. We account for linear loss and nonlinear loss of third order (two-photon absorption, 2PA) and fifth order, most notably 2PA-induced free carrier absorption (FCA). From this, we derive an upper bound for the output power of continuous-wave Brillouin-lasers and show that the optimal operating conditions and maximal realisable Stokes amplification of any given waveguide structure are determined by a dimensionless parameter ℱ involving the SBS-gain and all loss parameters. We provide simple expressions for optimal pump power, waveguide length and realisable amplification and demonstrate their utility in two example systems. Notably, we find that 2PA-induced FCA is a serious limitation to SBS in silicon and germanium for wavelengths shorter than 2200nm and 3600nm, respectively. In contrast, three-photon absorption is of no practical significance.}, language = {en} } @article{PomplunBurgerZschiedrichetal.2016, author = {Pomplun, Jan and Burger, Sven and Zschiedrich, Lin and Gutsche, Philipp and Schmidt, Frank}, title = {Method for fast computation of angular light scattering spectra from 2D periodic arrays}, volume = {9778}, journal = {Proc. SPIE}, arxiv = {http://arxiv.org/abs/1603.04169}, doi = {10.1117/12.2219666}, pages = {977839}, year = {2016}, language = {en} } @article{GutschePoulikakosHammerschmidtetal.2016, author = {Gutsche, Philipp and Poulikakos, Lisa and Hammerschmidt, Martin and Burger, Sven and Schmidt, Frank}, title = {Time-harmonic optical chirality in inhomogeneous space}, volume = {9756}, journal = {Proc. SPIE}, arxiv = {http://arxiv.org/abs/1603.05011}, doi = {10.1117/12.2209551}, pages = {97560X}, year = {2016}, language = {en} } @misc{GutscheLaeuterSchmidt2016, author = {Gutsche, Philipp and L{\"a}uter, Matthias and Schmidt, Frank}, title = {Parameter-dependent Parallel Block Sparse Arnoldi and D{\"o}hler Algorithms on Distributed Systems}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-58202}, year = {2016}, abstract = {We summarize the basics and first results of the analyses within our ZIB Bridge Project and give an outlook on further studies broadening the usage of hardware acceleration within the Finite Element Method (FEM) based solution of Maxwell's equations.}, language = {en} } @inproceedings{GregersendeLassonFrandsenetal.2017, author = {Gregersen, Niels and de Lasson, Jakob Rosenkrantz and Frandsen, Lars Hagedorn and Kim, Oleksiy S. and Breinbjerg, Olav and Wang, Fengwen and Sigmund, Ole and Ivinskaya, Aliaksandra and Lavrinenko, Andrei and Gutsche, Philipp and Burger, Sven and H{\"a}yrynen, Teppo and Merk, Jesper}, title = {Comparison of five numerical methods for computing quality factors and resonance wavelengths in photonic crystal membrane cavities}, booktitle = {CLEO/Europe-EQEC}, doi = {10.1109/CLEOE-EQEC.2017.8087750}, year = {2017}, language = {en} }